New Shingles placed over the original shingles

In order to cut down on labor cost would it be ok to have the roofing contractor not scrape off the old shingles, but nail or staple the new shingles on top of the old shingles? Does anyone know if this has been done before?

Advertisement

New Shingles placed over the original shingles

It's been done and if done properly it works.
The problem is most roofers think all you do is nail new shingles over top the existing and walk away, which results in a high percentage failure rate.

I have lay overs I did in the 80's & 90's still intact today so I know hands on they work, but you need to make sure the roofer you hire or you yourself if this is a diy project takes the proper steps to install it properly.

You can get the basic information from the shingle manufacturers website.

Advertisement

New Shingles placed over the original shingles

My current home had three layers of asphalt shingles on the roof when I bought it, so it is "possible." I think current codes allow for two layers, but make sure it's not going to void the manufacturers warranty..

__________________
That's just my opinion. But it's free, so take it for what it's worth to you.

New Shingles placed over the original shingles

It is legal in Il to shingle over an existing roof. Mine has 2 layers. Done about 6 yrs ago. The only place nearby that does not allow 2 layers, that i know of, is a town where the houses are built with trusses 2' on center and 3/8 plywood for sheathing

New Shingles placed over the original shingles

I think you need to consider this based on other things: For one - why are you re-shingling your roof? Has it been leaking or damaged? Will smacking a 2nd layer of roofing on top of a damaged layer REALLY fix the problem? What will you do if it doesn't - or if it even makes a problem worse?

We had serious roof/water damage a few years back from a tornado storm cell that tossed the kid's basketball goal onto the roof - they removed the original layer, and I saw the roof damage from the impact and brought it up as a concern. We were able to get that taken care of - having no singles on the roof helped them fix it more appropriately and address ALL the structural issues.

If you want to save money - scrape off the first layer yourself - or don't consider your roofing needs to be a 'save money to get it done more cheaply' project.

__________________

At this present moment in time I am making cabinets for the kitchen - just in case you wanted to know what I'm doing when I'm not around.

New Shingles placed over the original shingles

So, jwrob, the first thing to do is check with your local building department, to see if it is feasible in your area. The next thing that I would do is a detailed inspection of the entire roof system. Shingles are what most people see and think of when they look on top of their home, but laying shingles is only part of the trick. If water has gotten past the shingles, or looks like it has, you may have sheathing to replace. There are also valleys and flashings to consider, and there are times, depending on how the work was performed in the first place, that it is easier and better to strip everything off than it is to try to work around areas that may not be right to start with. After that, if you decide not to strip the old roof, it is a matter of the manufacturers recommendations.

New Shingles placed over the original shingles

The second or third layers will not last as long or look as good as a new layer.

The manufacturers know this and secondary applications will void most warrantees.

In areas with highly variable temperature ranges and ventilated attics/roofs, lime MN, where the air temperatures can range form -20F t0 -30F in the winter to 95+ in the summer, there is a lot of movement. Everyone knows how hot a roof surface in the sun can get and many people do not realize how cold a roof surface (dark shingles on a cold winter night) that magnify the movement. It is not unusual here to have a clean roof with -20F that can get even colder because we do not always the protection of snow like people further south. Unfortunately the insulated roof is not really viable, so temperatures range.

Maybe that is why many cooler states require compete tear-offs and starting fresh with no accumulated poor details or installations.

New Shingles placed over the original shingles

Quote:

Originally Posted by MJW

Make sure it is legal in your area. Here in MN it is illegal for a Contractor to install a second layer. Most of the states around us are the same.

I think this same law prevails in michigan i see lots of roofs all over the state in the process, ALL of them get tear- offs first. They USED to always do a re-roof here, if prior roof was good and flat. bob s